As indicated, the invention is particularly useful in controlling the speed of a direct current motor. Many systems presently employed, utilize electrical devices such as variable rheostats for regulating a steady flow of current to the motor being operated. In such devices, power is lost, or dissipated in heat caused by the resistance in the circuit. Then too, the shaft of the motor rotates at relatively little torque at low operating speeds of the motor. This is readily apparent when slight pressure is applied to the rotating shaft of the motor at such speeds.
The invention is designed to substantially eliminate the disadvantages indicated above by utilizing what might be termed a mechanically operated apparatus for sending pulsations or surges of direct electrical current to the motor, rather than regulating a steady flow of current to the motor.
Briefly stated, the invention contemplates using a pair of breaker points for opening and closing a circuit containing a direct current motor. Means are provided for varying the frequency of contact between the points and the period of time the points are in contact, to regulate the frequency and strength of the pulsations of current transmitted to the motor. A capacitor in circuit with the motor, is charged and discharged as the breaker points move into and out of contact. The capacitor, when discharging, sends the pulsations of current to the motor.